Give reasons for the following:
(a) The reverberation time of a hall used for speeches should be very short.
(b) A vibrating body produces sound. However, no sound is heard when a simple pendulum oscillates in air.
(c) Sounds of same loudness and pitch, but produced by different musical instruments such as violin and flute are distinguishable.
(a) The time for which the sound persists in the atmosphere after the sound has stopped producing from the source is known as Reverberation time. If reverberation time of a hall is long, then the multiple echoes produced would interfere with the original sound, and the speeches would not be heard clearly and distinctly.
(b) Sound is produced only when the frequency of the wave is greater than 20 Hz. As a simple pendulum produces waves less than 20Hz they cannot be heard.
(c) The quality or timbre is the characteristic which helps in distinguishing two sounds of same pitch and loudness. So, the musical instruments like violin and flute produces distinguishable sound.